On 09/11/2017 16:22, Radim Krčmář wrote: > 2017-11-08 14:32+0200, Eyal Moscovici: >> Some guests use these unhandled MSRs very frequently. >> This cause dmesg to be populated with lots of aggregated messages on >> usage of ignored MSRs. As ignore_msrs=true means that the user is >> well-aware his guest use ignored MSRs, allow to also disable the >> prints on their usage. >> >> An example of such guest is ESXi which tends to access a lot to MSR >> 0x34 (MSR_SMI_COUNT) very frequently. >> >> In addition, we have observed this to cause unnecessary delays to >> guest execution. Such an example is ESXi which experience networking >> delays in it's guests (L2 guests) because of these prints (even when >> prints are rate-limited). This can easily be reproduced by pinging >> from one L2 guest to another. Once in a while, a peak in ping RTT >> will be observed. Removing these unhandled MSR prints solves the >> issue. >> >> Because these prints can help diagnose issues with guests, >> this commit only suppress them by a module parameter instead of >> removing them from code entirely. >> >> Signed-off-by: Eyal Moscovici <eyal.moscovici@xxxxxxxxxx> >> Reviewed-by: Liran Alon <liran.alon@xxxxxxxxxx> >> Reviewed-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx> >> Signed-off-by: Krish Sadhukhan <krish.sadhukhan@xxxxxxxxxx> >> Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@xxxxxxxxxx> >> --- >> arch/x86/kvm/x86.c | 17 +++++++++++++---- >> 1 file changed, 13 insertions(+), 4 deletions(-) >> >> diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c >> index 03869eb..21c0059 100644 >> --- a/arch/x86/kvm/x86.c >> +++ b/arch/x86/kvm/x86.c >> @@ -107,6 +107,9 @@ >> static bool __read_mostly ignore_msrs = 0; >> module_param(ignore_msrs, bool, S_IRUGO | S_IWUSR); >> >> +static bool __read_mostly suppress_ignore_msrs_prints = false; >> +module_param(suppress_ignore_msrs_prints, bool, S_IRUGO | S_IWUSR); > > What about calling it 'print_ignored_msrs' and default to true? Makes sense! s/print/report/ perhaps? Thanks, Paolo > (I can change that when applying.) > > Thanks. >
